Disposable prefilled syringe assemblies for dispensing parenteral pharmaceuticals by injection are not new per se. Many syringe assemblies have been proposed which employ a glass tube filled with the desired medicaments. At one end of the glass tube is a plunger tip which functions as a seal prior to axial movement of the plunger tip to empty the contents of the syringe. At the other end of the glass tube or vial is a seal, often in the form of a elastomeric disk held in place by a plastic or metal cap. A plunger rod is generally associated with the plunger tip, and in many cases, the plunger tip and plunger rod are not fixedly attached to one another but are assembled at the time of intended use of the syringe assembly. One such device is shown in U.S. Pat. No. 3,967,759.
The needle design which is often times used with disposable prefilled syringe assemblies involves the use of a double ended needle assembly which is attached to the sealed end of the glass vial in a first position where the needle is aligned with but not penetrating the seal. The needle assembly then is movable to a second position whereby the interiorly pointing end of the needle penetrates the seal and provides access to the contents. The other end of the needle which is, of course, the end through which the medicine is administered to the patient, is covered by a needle cover or needle shield. One such design is shown in U.S. Pat. No. 3,739,779.
These and other designs of similar structure are complicated and/or oversized. Other designs have certain functional disadvantages and drawbacks, particularly when a single selfcontained assembly is needed.
None of these patents disclose or suggest a device which is totally suitable as a disposable prefilled syringe assembly. Particularly, none of the prior art provides a compact assembly which is provided with a functional locking mechanism to prevent inadvertent movement or damage to seals at either end of the prefilled container. It would be of great advantage if a syringe assembly could be provided which could be prefilled and stored or transported for a long period of time, followed by quick and efficient use when needed. Accordingly, it is an object of the present invention to provide such a device.